I. INTRODUCTION
This study deals with specific features and aspects of high task load management by small professional teams working in high risk environments such as a NPP control room. Professional teams' efficacy does not only rely upon technical knowledge but also depends upon non-technical (social and cognitive) skills. The final objective of our research is to identify the critical non-technical skills associated with observable behavior markers, highlighting the main conditions for successful coordination of joint actions in teams. Several researchers identified non-technical skills in different high risk environments (Flin, R., Crichton, M.T., 2004; Flin, R., Goeters, K.M., Hörmann H.J., Martin, L., 1998). From the core concept of these studies the communication and information sharing are mainly emphasized, hence the central focus of our present research is team interaction, especially operator team communication. Individuals as well as teams working in NPP areas are exposed to several stressors. Communication plays an important role how team members manage threatened situations, in this vein the most appropriate way to analyze how teams treat stressful events is to measure communication dimensions varying under different levels of task load (Gudela, G., Zala-Mezö E., 2004). Task load as a demand is inherent in the objective circumstances, like complexity, uncertainty, characteristics of working on nuclear sites. From many of identified sources of stress in NPP settings, the relevance of novelty, uncertainty and time pressure must be emphasized (Mumaw, R. J., 1994). NPP operators during their work, has to be on continuous alert. This readiness can intensively load the members of a team, due to the possibility of a new emerging event (such as a mechanical failure, system failures), if the appropriate actions are not known immediately. The effects of time pressure (inappropriately high risk taking) and other stressors mentioned above may lead to serious consequences from material damage to – in the worst case – environmental catastrophe.